The signal is fixed, meaning once it is there, it would not change regardless next month price. The idea is to buy or sell at last day of the month the signal is issued. A typical portfolio is diversified, meaning that it has a mix of different assets like US stock, foreign stock, bond, etc. This method can be applied to all assets. One can do dollar average in and out, but I really have no idea if that makes any difference over long period of time.